When I view Host Details, I’ve noticed that the Last Check for some of my hosts are not being updated, while others are. The only difference in the configurations is the hostnames. What could cause this?
In short: Hosts get checked only if the services on the host fail.
Please search the forum for a more detailed explanation. 
Luca
You also should check your time period entries…it could be that you set some differently and they are only going to be checked durring non-working hours.
You should also read the url I posted, since you have missed a very important detail about how nagios works. As luca stated, “nagios does NOT check host’s unless…”
thanks for the responses. i did a lot more reading and went through the logs and saw that the hosts that were updating were getting occasional service errors. i have a better understanding of how it works and you’ve helped clear up some of my misunderstandings.
Well don’t feel like a loner. It took me 2 weeks I think to figure out that the hosts are not going to be checked. Reading isn’t my strong point.
2 weeks??? i think it was more like six months… 
exactly when i found this forum… ghghgh
Luca
And luca has been nothing but a nagios nut ever since too!!!